2008 Chevy uplander lt
 

I am having trouble with a 2008 uplander LT with 30k miles. I keep getting a check light that is showing a po449 code which display's Solenoid Circuit Malfunction and a po455 code which display's a Gross leak. I have changed the oem gas cap and it helped for a while. I am thinking of changing the Vapor canister, the Solenoid Valve and the purge valve.
I have read several of the threads which have done the same with no correction. Has there been any history of this problems and what if any was the fix. Does anyone have sugestions.
Thanks for your help. :)

Welcome to the forum,
You may want to check with your local dealer as it sounds like you are still under warranty and most all emissions items are covered....

+1 on the dealer. 3yr-36K bumper-to-bumper warranty. Where do you live, Pops?